Sialon and zirconia-toughened alumina (ZTA) ceramics were evaluated as roller followers in simulated valve train tests. The tests measured the load-carrying capacity of the ceramic rollers by determining when incipient seizure occurred on the steel shaft. The test results revealed that the ZTA rollers exhibited a greater load-carrying capacity compared to the sialon rollers, which was due to the surface texture of ZTA rollers. The bore of the ZTA ceramics exhibited considerable grain pullout, providing cavities to retain the lubricant. It was also observed that a honed bore surface increased the load-carrying capacity of the ceramic rollers compared to the ground bore surface, particularly with the sialon rollers. The diametral clearance had no discernable effect on the maximum load-carrying capacity for the range of clearances tested, which is contrary to analytical models.Presented at the 48th Annual Meeting in Calgary, Alberta, Canada May 17–20, 1993